Valve-gear for steam-engines.



DAVIDSON & w. -0. LARMUTH.

VALVE GEAR FOR STEAM ENGINES.

APPLICATION FILED JUNE 12,1911.

Patented July 23, 1912.

2 SHEETS-SHEET 1.

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J. DAVIDSON & w. 0.. LARMUTH. VALVE GEAR FOB. STEAM ENGINES.

APPLICATION FILED JUNE 12, 1911.

1,033,676. Patented July 23, 1912.

2 SHEETSSHEET 2.

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A'IES ran JOHN DAVIDSON, OF PENDLETON, AND WILLIAM OLIVER LABMUTH, 0FSALFORD, ENGLAND.

VALVE-GEAR FOB STEAM-ENGINES.

To all whom it may concern:

Be it known that we, JOHN DAVIDSON and VILLIAM OLIVER LARMUTH, subjectsof the King of Great Britain, residing at Pendleton and Salford,respectively, both in the county of Lancaster, Kingdom of Great Britain,have invented certain new and useful Improvements in Valve-Gear forSteam- Engines; and we do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

This invention relates to improvements upon an invention for which anapplication for Letters Patent John Davidson one of the applicants hasmade for improvements in valve gear in high speed vertical engines ofthe type in which drop valves, combined drop and piston valves or simplepiston valves are employed, said improvements being for the purpose ofenabling the valves to be actuated direct from the crank shaft. In thesaid invention the valve is connected to a plunger, and a roller isfitted on the bottom end of a plunger, said roller resting on a camformed on one end of a pivoted lever, whose opposite end is fitted onthe rod of an eccentric that is fitted on the crank shaft.

In practice it has been found that in the case of engines with cylindersarranged to exhaust in the center by the piston uncovering ports, it isnecessary to provide a means for relieving the compression pressure whenthe vacuum fails and the engine has to exhaust to atmosphere.

The object of our invention is to provide means for causing the steamadmission valves to automatically open just at the moment thecompression pressure reaches the initial steam pressure, and letting thepiston deliver the steam into the steam chest which necessitatesincreasing the lead of the valve. e attain this object by the meansillustrated in the accompanying two sheets of drawings in which Figure lshows a part sectional side view of the device on an enlarged scale, andFig. 2 shows an elevation of an engine provided with the said device.

Similar letters refer to similar parts throughout the several views.

In carrying out our invention and referring to the drawing, in lieu ofrigidly connecting the roller a to the said plunger, it is Specificationof Letters Patent.

Application filed June 12, 1911.

Patented July 23, 1912.

Serial No. 632,713.

attached to the same by a link Z), and caused to be moved so as to catchthe raised portion of the cam d earlier and thereby open the valveearlier by connecting said roller to one end of a link 0, whose oppositeend is eccentrically pivoted at e on a shaft j which is connected by acrank g and link it to the piston 2' of a small cylinder is, which whenWorking under normal conditions is retained at one end of the cylinderby a spring Z. Attached to the end of the cylinder is or in anyconvenient position is a diaphragm m coupled to a valve 12. in thecylinder 70. One side of the diaphragm m closes a suitable chamber 0which is connected to the exhaust pipe of the engine at 79 and the otheris open to the atmosphere. At one end of the cylinder 70 between thevalve and the diaphragm is connected an oil pressure main, or steam pipe9 or any suitable fluid pressure. IVhen the vacuum is good the pressureof the atmosphere will keep the valve a closed, but immediately it failsthe pressure of oil or steam or other fluid will open the valve n andenter the cylinder and cause the piston z' to move to the other end, andby means of the link 0 will cause the valve of the engine that isactuated by the roller (4 and cam d to open earlier as alreadydescribed. By these means when as a result of the vacuum failing inunifiow steam engines, the compression greatly increases the lead of themain valve, and the steam is returned to the chest immediately it isequal in pressure.

We do not confine ourselves to the precise construction shown on thedrawing as this may be modified without departing fro our invention.

We claim:

1. In a steam engine valve gear, a steam admission valve spindle, a linkon the said spindle, an admission valve operating cam acting directly onthe said link, means for altering the position of the said link inrelation to the said cam, a piston connected to the said means, acylinder around the said piston, a valve controlling the inlet of steamto the said piston, and a diaphragm one side of which is incommunication with the atmosphere and the other side with the exhauststeam for controlling the said valve, substantially for the purpose setforth.

2. In a steam engine valve gear, a steam admission valve spindle, anadmission valve operating cam acting directly on the said link, a rodconnected to the said link, a shaft, an eccentric pin on the said shaftand connected to the said rod, a crank on the said shaft, a connectingrod connected to the said crank, a piston rod connected to the saidconnecting rod, a piston connected to the said piston rod, a cylinderaround the said piston, a spring inside the said cylinder, and pressingagainst one side of the said piston, a valve in the said cylinder forcontrolling the inlet of live steam, a pipe connecting the said valvewith the live trolling the said valve, substantially for the purpose setforth.

In testlmony whereof we have afiixed our signatures in presence of twowitnesses.

JOHN DAVIDSON. WILLIAM OLIVER LARMUTH.

Witnesses:

FERDINAND B. BOSSI-IARDT, STANLEY E. BRAMALL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G,

